1. Field of the Invention
The present invention relates generally to the field of artificial ocean reefs, and more specifically to a modular reef structure formed of boulders and concrete, providing protective crawl spaces, ledges and overhangs which approximate naturally occurring outcrops of coral and form complex habitats for various aquatic organisms, and providing irregular surfaces suitable for attachment and growth of aquatic plant life and natural coral formations, and to a method of manufacturing the same, these structures taking the form of hollow domes having venturi assisted ventilation ports and hidden entrances to protect the inhabiting organisms from divers and natural predators, and elongate cubes having restricted passageways, selected and sized to suit a particular ocean environment, for promoting the formation of new and complete ecosystems.
2. Description of the Prior Art
The earth is covered with a vast community of life, all in continuous flux and sustained by the energy of the sun. This community is joined together by complex and varied life cycle which cross the boundary between land and sea. Man has come to recognize his place in global community and the importance of maintaining its many facets. One such facet which has received increasing attention is the ocean reef and its unique chain of life. This awareness has accelerated quickly in recent decades with the rapid advances in scientific knowledge and diving equipment, but began much earlier.
Since prehistory man has attempted to explore the sea. His initial curiosity led to ocean travel for conquest and trade, and to fishing and clam diving. Homer compared the fall of Hector's charioteer in the Iliad with the descending movement of an oyster diver. Attempts at ocean exploration for its own sake have paralleled utilitarian incursions. In ancient Assyria men tried to submerge themselves by sinking on goatskin bellows. Alexander the Great is said to have observed sea creatures from within a glass barrel, more than two thousand years ago. Leonardo da Vinci sketched primitive diving lungs. By the nineteenth century the development of the force pump for providing an air supply and the steel diving helmet permitted extended submersion and exploration. During World War II, the ingenuity of Jacques-Yves Cousteau, a French naval officer, led to the perfection of the self-contained underwater breathing apparatus, or scuba.
The increased access to ocean depths has revealed to man a rich pageantry of life never before imagined. The ocean reef, which was once merely considered a hazard for sea-going vessels, was transformed into a source of fascination and study. In recent years man has begun to recognize his own destruction of these unique aquatic communities and attempted to preserve and restore their original beauty and variety.
A number of inventions intended to achieve this goal have been developed and patented over the years. One is that of Van Doren, U.S. Pat. No. 4,997,311, issued on Mar. 5, 1991. Van Doren teaches an artificial reef including a thin-walled, plastic hemispherical dome, perforated by several access ports. The circular edge of the dome is turned diametrically outward and back to form a circumferential trough. The domes are transported by ship to the site of deployment and the trough is fitted with engaging hooks and filled with cement. After the cement cures, the hooks are tied to a hoist and the dome is lifted, swung out over the water and dropped. The concrete in the trough pulls the circular edge downward, while the access ports permit water to flow through the dome with some drag. In this way Van Doren parachutes down to the bottom in an upright position. A problem with Van Doren is that the plastic structure does not provide a naturally textured surface to encourage attachment of ocean plant life and coral-forming polyps. The smooth surface also fails to provide a complex habitat for smaller organisms. Still another problem is that the plastic degrades in an ocean environment.
Lenson, U.S. Pat. No. 4,978,247, issued on Dec. 18, 1990, discloses a concrete breakwater structure for placing on beaches to prevent erosion. Two essentially triangular end panels are joined by broad, inclined front and rear panels, each having several holes for receiving some of the wave and dissipating the impact. A projecting top panel is also provided for structural integrity and to further dissipate wave action. Lenson may be elevated on leg extensions. A problem with Lenson is that it is not designed to function as an artificial reef. Were the structure placed on an ocean floor, the directly aligned multiple holes would permit rapid currents to flow through and prevent habitation by certain organisms. The interior of the structure would also be accessible to divers and other predators. Finally, all surfaces are smooth, limiting habitat complexity.
Jones, U.S. Pat. No. 4,913,094, issued on Apr. 3, 1990 reveals an artificial reef in the form of corrugated sheets of polyvinyl chloride plastic (PVC). These sheets are joined together face to face so that the corrugations extend transverse to each other and form enclosed spaces for receiving fish and shell fish. A concrete base acts as an anchor to guide the reef to the ocean floor and to maintain its upright orientation. A problem with Jones is that, whether made of PVC or steel, the sheets are not durable in comparison with concrete structures. This means limited reef life and vulnerability to intruding divers in search of inhabiting fish. Another problem is that the sheets do not provide a natural material and a truly irregular surface conducive to attachment of epifauna and coral-forming polyps.
Suzuki, U.S. Pat. No. 4,508,057, issued on Apr. 2, 1985, discloses an algal culturing reef unit. The unit includes concrete blocks having a porous layer of iron sulfate penetrating inside the concrete. This layer is intended to create acid to neutralize the strong alkali of concrete. Crystal pellets of iron sulfate are pressed into the wet cement during manufacture and dissolve while the blocks cure. A reef design is also provided having a series of parallel planar concrete slabs joined together in a spaced apart relationship. A problem with Suzuki is that aquatic organisms are left unprotected from natural predators and divers. Another problem is that Suzuki does not present the appearance of a natural reef nor offer the deep irregularities which are attractive to various fish. As to the iron sulfate feature for neutralizing the alkali content of the concrete, the resulting formation of large quantities of algae may displace and discourage habitation by many desired species.
Schaaf, U.S. Pat. No. 4,367,978, issued on Jan. 11, 1983, teaches a concrete structure for preventing beach erosion. The structure is a prism-shaped module containing at least one converging passageway, for receiving and breaking up waves, and slowing the flow rate of the water. It also has oppositely inclined front and rear walls to break waves and serve as an off-shore, reef-like barrier. A problem with Schaaf, if used as an artificial reef, is that the passageways are open and easily accessible, so that inhabiting organisms have no protection from predation. Another problem is that currents can readily flow through the passageways at a rapid rate, preventing the anchoring of epifauna and the formation of a suitable habitat. Still another problem is that all surfaces are relatively smooth, and thus dissimilar to those of natural reefs.
O'Neil, U.S. Pat. No. 4,269,537, issued on May 26, 1981, teaches another concrete structure designed to function as a wave-absorbing barrier. O'Neil includes an essentially flat, rectangular base having a trapezoidal cross-section and four leg members. A plurality of these structures are placed along a shoreline in staggered fashion to break the impact of waves. O'Neil shares the problems identified above for Schaaf.
Pranis, U.S. Pat. No. 3,898,958, issued on Aug. 12, 1975, discloses a fish farming apparatus in the form of a framework of elongate members intended to function as an artificial reef. The members are joined by connector means to form basic units of a matrix, defining a series of open-sided cubes. The members may have a variety of different cross-sectional shapes, and surfaces roughened by sandblasting. Pranis is intended to provide stationary surfaces on which microorganisms can attach themselves and within which large and small fish may live. A problem with Pranis is that it does not resemble a natural reef and does not provide the large surface irregularities which may attract various aquatic organisms. Another problem is that the framework is open so that inhabitants are not protected from natural predators and divers. Still another problem is that the elongate members, whether formed of metal or plastic, are likely to deteriorate in an ocean environment.
Structures similar to Pranis and presenting the same general problems are disclosed in Japanese Patent Number 63-59826 and Japanese Patent Number 2-69124. Other foreign patents teaching various artificial reef and breakwater structures are: Japanese Patent Number 62-220130, Japanese Patent Number 61-96930, and Maheo, French Patent Number 1,174,670, Devin, French Patent Number 79 24207, and Carlet de la Roziere, French Patent Number 698,218, all apparently presenting problems similar to those identified above.
It is thus an object of the present invention to provide an artificial reef structure which resembles in overall shape, and provides irregularities similar to, those of naturally occurring reefs.
It is another object of the present invention to provide such a structure which offers shelter to various aquatic organisms through which water is circulated and which is capable of protecting them from natural predators and divers.
It is still another object of the present invention to provide such a structure which includes cavities to create habitats through which a slight circulating current is developed.
It is finally an object of the present invention to provide such a structure which is simple and relatively inexpensive to build and durable enough to last for many decades.